This invention relates to tube apparatus such as tube sealers. More specifically, this invention relates to a microprocessor controlled devices such as dielectric tube apparatus having reduced radio frequency emanations.
In a wide variety of applications and industries, there is a need to seal, connect, weld or otherwise manipulate tubes. For example, there is often a need to create a seal at a location along the length of a tube or a portion thereof. Such a seal may be desired to prevent or substantially reduce the flow of gaseous or liquid fluid between adjacent portions of a tube.
One example of an application in which a tube may be desired to be sealed is the sealing of tubes that contain blood or other bodily fluids. For example, blood may be drawn from a donor from flexible tubing that extends into a plastic blood collection bag. Once the bag is filled to its capacity, it may be desired to seal the tubing in order to prevent leakage and/or contamination or deterioration of the collected blood. After such collection, the blood may need to be typed and/or tested under various criteria. In order to provide a representative supply of blood for such typing and test purposes, a plurality of segments of the tubing may be sealed from one another to provide multiple sealed samples. Such samples may later be separately opened for typing and/or testing purposes.
Systems have been proposed to seal tubes using a pair of jaws such as electrodes for compressing tubing while applying radio frequency energy to melt the tubing and form a weld to effect a seal. Such systems generate a substantial quantity of radio frequency (RF) energy in order to heat and melt the plastic of the tubing sufficiently to form a weld. More specifically, a burst of RF energy may be transmitted across the jaws. The tubing represents a resistance to the RF energy transmitted therethrough and a capacitance between the jaws resulting in the development of heat to partially melt or soften the tubing and weld the opposing tubing surfaces to one another.
Radio frequency energy is considered to be electromagnetic energy at any frequency in the radio spectrum between 9 kHz and 3,000,000 MHz. Because of emissions or emanations from devices that generate RF energy, such devices should be constructed in accordance with good engineering design and manufacturing practice. It is also recognized that emanations from such devices should be suppressed as much as practicable. The United States has promulgated regulations to limit the level of emanations from such devices. Reference is made to Chapter 1 of Title 47 of the Code of Federal Regulations.
The foregoing comments apply not only to dielectric tube sealers but also to any apparatus configured to connect, weld, or otherwise manipulate tubes using radio frequency, heat, mechanical elements, or any other known means for manipulating tubes.
According to one aspect, this invention provides a tube sealer adapted to limit radio frequency emanations during operation. An exemplary embodiment of such a tube sealer may include an enclosure and first and second jaws oriented with respect to the enclosure to receive a tube therebetween. The first jaw is fixed and coupled to a radio frequency generator, and the second jaw is movable with respect to the first jaw and coupled to ground potential. The tube sealer also may include a shield positioned adjacent the enclosure and configured to at least partially enclose the first and second jaws yet permit the introduction of a tube portion to a position between the first and second jaws. The shield thereby reduces radio frequency emanations from the first and second jaws. The shield can be movable with respect to the enclosure to at least partially expose the first and second jaws (e.g., for cleaning and maintenance purposes).
According to another aspect, this invention provides a tube sealer adapted to detect successful or failed seals. One exemplary embodiment of such a tube sealer may include jaws mounted for movement with respect to one another between (1) a first position spaced from one another to receive a tube portion and (2) a second position proximal one another to compress a tube portion, wherein the jaws in the second position define a gap selected to form a successful seal. The tube sealer may also include a sensor positioned to detect when the jaws have moved into the second position. Finally, the tube sealer may further include a timer electrically coupled to the sensor for determining the time delay before the jaws have moved into the second position, wherein a time delay up to a predetermined time limit indicates a successful seal and a time delay exceeding the predetermined time limit indicates a failed seal.
According to yet another aspect, this invention includes a tube sealer that is programmable to control the area of a seal. An exemplary tube sealer according to this aspect of the invention may include a radio frequency generator configured to generate radio frequency for a time period. The tube sealer may also include jaws mounted for movement with respect to one another, one of the jaws being coupled to the radio frequency generator. The tube sealer may also include a microprocessor configured to control the radio frequency generator, wherein the microprocessor is programmable to select the time period during which radio frequency is generated by the radio frequency generator, thereby controlling the area of the seal formed in a tube.
According to still another aspect, this invention provides a method for controlling the area of a seal formed in a tube by means of a tube sealer having a radio frequency generator and jaws mounted for movement with respect to one another. The method includes the steps of selecting a tube for sealing and programming a microprocessor to select the time period during which the radio frequency is generated, thereby controlling the area of a seal formed in the tube.